Electronic element package and method for manufacturing the same

ABSTRACT

The present disclosure relates to an electronic element package and a method of manufacturing the same. The electronic element package includes a substrate, an element disposed on the substrate, and a cap enclosing the element. One of the substrate and the cap includes a groove, the other of the substrate and the cap includes a protrusion engaging with the groove. A first metal layer and a second metal layer form a metallic bond with each other in a space between the groove and the protrusion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional of U.S. application Ser. No. 15/275,603filed on Sep. 26, 2016 which claims benefit under 35 USC 119(a) ofpriority to Korean Patent Application No. 10-2016-0032183 filed on Mar.17, 2016 in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated herein by reference in its entirety.

BACKGROUND 1. Field

The present disclosure relates to an electronic element package and amethod for manufacturing the same.

2. Description of Related Art

Recently, with the recent rapid development of mobile communicationsdevices, the demand for macrofilters, oscillators, and other componentshas increased. For example, bulk acoustic wave (BAW) resonators havebeen regularly used to implement macrofilters, oscillators, and othercomponents. Using BAW resonators have advantages such as enabling massproduction at low cost and allowing for macrominiaturization.Furthermore, BAW resonators enables a high quality factor to be obtainedand may be used in macrofrequency bands.

In general, because performance of resonators (vibrators) of BAWresonators degrade at a bonding temperature of 500° C. or more, the BAWresonators need to be hermetically sealed at a low temperature of 500°C. or less. Thus, thermal diffusion bonding, eutectic bonding or silicondirect bonding may be applied.

Furthermore, BAW resonators often use thermal diffusion bonding in a capbonding process. Thermal diffusion bonding is defined as a method ofspreading materials to be bonded, for example, bonding metals, on twosurfaces of wafers and pressing the wafers using heat and strong forceto bond the wafers. The strong force first functions to press the waferstogether to have a gap having a nano size or less so that the spreadbonding metals are in close proximity to each other and fuse together.When the pressed wafers are heated, the bonding metals formed on therespective wafers fuse together so that the wafers may be bonded.

In this example, the spread bonding metals represent membrane thicknessdistribution within the wafers depending on membrane conditions, and thethicknesses of the wafers that form a base of the bonding metals andhave a constant degree of thickness distribution. In order to press thewafers having such thickness distribution against each other, a highdegree of force is required, and a bonding metal that has high ductilityand that may be relatively easily transformed by the same degree offorce is needed. Furthermore, equipment able to perform a bondingprocess requires a high degree of pressure. Moreover, inch-up processesfor substrates are required such that microelectromechanical systems(MEMS) devices including up-to-date BAW resonators are of reasonablecost. For the inch-up processes, bonding pressure needs to be increasedin proportion to inch-up.

Furthermore, such thermal press bonding may be performed under thecondition that a surface to be bonded is required to have a surface in apure state in which oxidation has not occurred. Thus, Au—Au diffusionbonding is used, in which oxidation barely occurs and provides excellentductility at high temperatures and under atmospheric conditions. Use ofAu—Au diffusion bonding results in an increase in manufacturing costs.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

In accordance with an embodiment, a bonding structure and method thereofare configured to include bonding a metal layer covering a protrusionformed on one side of a bonding portion to a metal layer covering agroove formed on another side of the bonding portion.

In accordance with an embodiment, there is provided an electronicelement package including: a substrate; an element disposed on thesubstrate; and a cap enclosing the element, wherein one of the substrateand the cap may include a groove, the other of the substrate and the capmay include a protrusion engaging with the groove, and a first metallayer and a second metal layer forming a metallic bond with each otherin a space between the groove and the protrusion.

The groove may include an inclined wall surface, and the metallic bondmay be a bond between a portion of the first metal layer covering anedge of the protrusion of the first metal layer and a portion of thesecond metal layer covering the inclined wall surface of the groove ofthe second metal layer.

The metallic bond may include a metal thermal diffusion layer.

The first metal layer and the second metal layer may include a same typeof material.

The substrate and the cap may include a resin layer disposed in a spacetherebetween to form a resin bond.

The resin layer may include an epoxy resin.

The electronic element package may be a BAW resonator.

In accordance with another embodiment, there is provided a method ofmanufacturing an electronic element package including: forming anelement on a surface of a substrate; and bonding a cap enclosing theelement to the substrate, wherein one of the substrate and the cap mayinclude a groove, the other of the substrate and the cap may include aprotrusion engaging with the groove, and the bonding the cap to thesubstrate may include metallically bonding a first metal layer to asecond metal layer, formed in a space between the groove and theprotrusion.

The groove may include an inclined wall surface, and the metallicallybonding of the first metal layer to the second metal layer may includebonding a portion of the first metal layer covering an edge of theprotrusion of the first metal layer to a portion of the second metallayer covering the inclined wall surface of the groove.

The metallically bonding the first metal layer to the second metal layermay be performed using a metal thermal diffusion bonding process.

The bonding the cap to the substrate further may include resin-bondingthe cap to the substrate using a resin layer.

The resin layer may be disposed on either one or both of the substrateand the cap before the resin-bonding, and may be disposed in a spacebetween the substrate and the cap after the resin-bonding the substrateto the cap.

In accordance with a further embodiment, there is provided an electronicelement package, including: an element disposed on a substrate; a capconfigured to cover the element on the substrate; a protrusion formed onone of a lower surface of a side wall of the cap or on an upper surfaceof the substrate; a first metal layer covering at least one surface ofthe protrusion; a groove formed on another of the lower surface of theside wall of the cap or on the upper surface of the substrate; and asecond metal layer covering the groove, wherein a metallic bond may beconfigured between at least a portion of the first metal layer and thesecond metal layer.

The groove may be a recess having an inclined wall side surface for linebonding and a flat surface as a bottom surface.

Upon the protrusion being formed on the lower surface of the side wallof the cap, the first metal layer extends from a predetermined point onthe lower surface of the side wall, covering side surfaces and a lowersurface of the protrusion, and extending to another predetermined pointof the lower surface of the side wall.

Upon the groove being formed on the upper surface of the substrate, thesecond metal layer extends from a predetermined point on the uppersurface of the substrate, covering inclined wall surfaces and a flatsurface of the groove, and extending to another predetermined point ofthe upper surface of the substrate.

A resin layer may be formed on the bonding surface of the side wall ofthe cap or the bonding surface of the substrate to resin-bond the lowersurface of the side wall of the cap to the upper surface of thesubstrate using the resin layer.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic plan view of an electronic device module, inaccordance with an embodiment;

FIG. 2 is a schematic cross-sectional view of an element package, inaccordance with an embodiment;

FIG. 3 is a schematic enlarged cross-sectional view of region A of FIG.2, in accordance with an embodiment;

FIG. 4 is another schematic enlarged cross-sectional view of region A ofFIG. 2, in accordance with an embodiment;

FIGS. 5 and 6 are schematic cross-sectional views of manufacturing anelectronic element package, in accordance with an embodiment;

FIG. 7 is a schematic cross-sectional view of manufacturing region A ofFIGS. 5 and 6, in accordance with an embodiment;

FIG. 8 is a schematic cross-sectional view of another example ofmanufacturing region A of FIGS. 5 and 6, in accordance with anembodiment;

FIG. 9 is a schematic cross-sectional view a bonding structure beingapplied to an uneven bonding surface, in accordance with an embodiment;and

FIG. 10 is a schematic cross-sectional view of a metallic bondingstructure.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent after an understanding of thedisclosure of this application. For example, the sequences of operationsdescribed herein are merely examples, and are not limited to those setforth herein, but may be changed as will be apparent after anunderstanding of the disclosure of this application, with the exceptionof operations necessarily occurring in a certain order. Also,descriptions of features that are known in the art may be omitted forincreased clarity and conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided merelyto illustrate some of the many possible ways of implementing themethods, apparatuses, and/or systems described herein that will beapparent after an understanding of the disclosure of this application.

Throughout the specification, when an element, such as a layer, region,or substrate, is described as being “on,” “connected to,” or “coupledto” another element, it may be directly “on,” “connected to,” or“coupled to” the other element, or there may be one or more otherelements intervening therebetween. In contrast, when an element isdescribed as being “directly on,” “directly connected to,” or “directlycoupled to” another element, there can be no other elements interveningtherebetween.

As used herein, the term “and/or” includes any one and any combinationof any two or more of the associated listed items.

Although terms such as “first,” “second,” and “third” may be used hereinto describe various members, components, regions, layers, or sections,these members, components, regions, layers, or sections are not to belimited by these terms. Rather, these terms are only used to distinguishone member, component, region, layer, or section from another member,component, region, layer, or section. Thus, a first member, component,region, layer, or section referred to in examples described herein mayalso be referred to as a second member, component, region, layer, orsection without departing from the teachings of the examples.

Spatially relative terms such as “above,” “upper,” “below,” and “lower”may be used herein for ease of description to describe one element'srelationship to another element as shown in the figures. Such spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. For example, if the device in the figures is turned over,an element described as being “above” or “upper” relative to anotherelement will then be “below” or “lower” relative to the other element.Thus, the term “above” encompasses both the above and below orientationsdepending on the spatial orientation of the device. The device may alsobe oriented in other ways (for example, rotated 90 degrees or at otherorientations), and the spatially relative terms used herein are to beinterpreted accordingly.

The terminology used herein is for describing various examples only, andis not to be used to limit the disclosure. The articles “a,” “an,” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. The terms “comprises,” “includes,”and “has” specify the presence of stated features, numbers, operations,members, elements, and/or combinations thereof, but do not preclude thepresence or addition of one or more other features, numbers, operations,members, elements, and/or combinations thereof.

Due to manufacturing techniques and/or tolerances, variations of theshapes shown in the drawings may occur. Thus, the examples describedherein are not limited to the specific shapes shown in the drawings, butinclude changes in shape that occur during manufacturing.

The features of the examples described herein may be combined in variousways as will be apparent after an understanding of the disclosure ofthis application. Further, although the examples described herein have avariety of configurations, other configurations are possible as will beapparent after an understanding of the disclosure of this application.

Electronic Device Module

FIG. 1 is a schematic plan view of an electronic device module, inaccordance with an embodiment.

Referring to FIG. 1, an electronic device module 1100 includes varioustypes of electronic components. For example, various types of passivecomponents 1140 and 1150 and an electronic element package 1130 aremounted around an integrated circuit (IC) chip 1120 on a printed circuitboard (PCB) 1110 of the electronic device module 1100. These componentsare electrically connected to one another through a circuit 1111, andvarious signals are transmitted or received through the circuit 1111.

The IC chip 1120 is a memory chip such as a volatile memory (forexample, a dynamic random access memory (DRAM)), a non-volatile memory(for example, a read only memory (ROM)), or a flash memory; anapplication processor chip such as a central processor (for example, acentral processing unit (CPU)), a graphic processor (for example, agraphic processing unit (GPU)), a digital signal processor, acryptographic processor, a microprocessor, a microcontroller, or thelike; and a logic chip such as an analog-to-digital converter (ADC), oran application-specific integrated circuit (ASIC). However, the presentdisclosure is not limited thereto, but the IC chip 1120 may also includeother types of chip related components. These chip related componentsare also combined.

The passive components 1140 and 1150 may be various types of filtersused to remove noise, for example, a power inductor, a high frequency(HF) inductor, a general bead, a GHz bead, a common mode filter, and thelike. However, the present disclosure is not limited thereto, and thepassive components 1140 and 1150 may be other passive components, suchas various types of capacitors. These passive components are alsocombined.

The element package 1130 includes various types ofmicro-electro-mechanical systems (MEMS) devices, and may be, forexample, a bulk acoustic wave (BAW) device, or a surface acoustic wave(SAW) device. However, the present disclosure is not limited thereto.These devices are used as filters to transmit or receive a radiofrequency (RF) signal. The element package 1130, according to anembodiment, may be such an RF filter. However, the present disclosure isnot limited thereto. The element package 1130 may also be other elementpackages to which a bonding structure described below is applied.

The electronic device module 1100 may be a typical Wi-Fi module.However, the present disclosure is not limited thereto. For example, theelectronic device module 1100 may be a module used in an electronicdevice, such as a smartphone, a personal digital assistant, a digitalvideo camera, a digital still camera, a network system, a computer, amonitor, a television, a video game console, or a smartwatch.

Electronic Element Package

An element package, according to an embodiment, will hereinafter bedescribed, and for convenience, the structure of a BAW resonator isdescribed with an example. However, the contents, according to anembodiment, may be applied to element packages having various differentpurposes as described above.

FIG. 2 is a schematic cross-sectional view of an electronic elementpackage, in accordance with an embodiment.

Referring to FIG. 2, an electronic element package 100, according to anembodiment, includes a substrate 110, an element 120, and a cap 140. Anair gap 130 is formed in a space between the substrate 110 and theelement 120, and the element 120 is formed on a membrane layer 150 to bespaced apart from the substrate 110 by the air gap 130.

The substrate 110 may be a silicon (Si) substrate, a high resistancesilicon (HRS) substrate, a gallium arsenide (GaAs) substrate, a glasssubstrate, a ceramic substrate, or a silicon on insulator (SOI).However, the present embodiment is not limited thereto.

The element 120 includes a first electrode 121, a piezoelectric layer123, and a second electrode 125. The element 120 is formed bysequentially stacking the first electrode 121, the piezoelectric layer123, and the second electrode 125 from or on the membrane layer 150.Thus, the piezoelectric layer 123 is disposed in a space between thefirst electrode 121 and the second electrode 125. The element 120 isformed on the membrane layer 150 and, resultantly, the membrane layer150, the first electrode 121, the piezoelectric layer 123, and thesecond electrode 125 are sequentially formed on an upper portion of thesubstrate 110.

The element 120 resonates with the piezoelectric layer 123 at a signal,applied to the first electrode 121 and the second electrode 125, togenerate a resonant frequency or a half resonant frequency. The firstelectrode 121 and the second electrode 125 are formed of metals, such asgold (Au), molybdenum (Mo), lutetium (Lu), aluminum (Al), platinum (Pt),titanium (Ti), tungsten (W), palladium (Pd), chromium (Cr), and nickel(Ni). However, the present disclosure is not limited thereto.

The element 120 uses acoustic waves generated by the piezoelectric layer123. For example, when a signal is applied to the first electrode 121and the second electrode 125, the piezoelectric layer 123 mechanicallyvibrates in a thickness direction thereof to generate acoustic waves. Inan embodiment, the piezoelectric layer 123 includes a zinc oxide (ZnO),an aluminum nitride (AlN), or quartz.

A resonance phenomenon of the piezoelectric layer 123 occurs when ½ ofan applied signal wavelength corresponds to the thickness of thepiezoelectric layer 123. When the resonance phenomenon occurs,electrical impedance rapidly changes, and an acoustic wave resonator,according to an embodiment, may be used as a filter that selects afrequency. The resonant frequency is determined depending on thethickness of the piezoelectric layer 123, the first electrode 121 andthe second electrode 125 surrounding the piezoelectric layer 123, or theparticular elastic wave velocity of the piezoelectric layer 123. As anexample, as the thickness of the piezoelectric layer 123 is reduced, theresonant frequency increases.

The element 120 further includes a protective layer 127. The protectivelayer 127 is formed on an upper portion of the second electrode 125 toprevent the second electrode 125 from being exposed to an externalenvironment. The first electrode 121 and the second electrode 125 areformed on opposite outside or exterior surfaces of the piezoelectriclayer 123, and are connected to a first connecting electrode 180 and asecond connecting electrode 190, respectively. The first connectingelectrode 180 and the second connecting electrode 190 confirm filtercharacteristics of a resonator, and perform required frequency trimming.The present disclosure is not, however, limited thereto.

The element 120 is spaced apart from the substrate 110 by the air gap130 in order to increase quality factor. For example, the air gap 130 isformed in a space between the element 120 and the substrate 110 so thatthe substrate 110 does not affect or influence acoustic waves generatedby the piezoelectric layer 123. Further, the air gap 130 allowsreflection characteristics of acoustic waves, generated by the element120, to be improved. As an empty space, the air gap 130 hasapproximately infinite impedance, and thus, acoustic waves are not lostor do not propagate in the air gap 130, and remain in the element 120.Thus, the air gap 130 enables an acoustic wave loss to be reduced in alongitudinal direction thereof, resulting in an increase in a qualityfactor value of the element 120.

A plurality of via holes 112 passing through the substrate 110 areformed towards a lower surface of the substrate 110. A first connectingconductor 115 a and a second connecting conductor 115 b are formedinside the via holes 112, respectively. The first and second connectingconductors 115 a and 115 b are formed on internal surfaces of the viaholes 112, that is, the entirety of a first inner wall 110 a and asecond inner wall 110 b of the substrate 110. However, the presentdisclosure is not limited thereto. One end of each of the first andsecond connecting conductors 115 a and 115 b is connected to externalelectrodes 117 formed on the lower surface of the substrate 110, and theother end thereof is connected to the first electrode 121 or the secondelectrode 125.

In an example, the first connecting conductor 115 a electricallyconnects the first electrode 121 to the external electrode 117, and thesecond connecting conductor 115 b electrically connects the secondelectrode 125 to the external electrode 117. Thus, the first connectingconductor 115 a is electrically connected to the first electrode 121through the substrate 110 and the membrane layer 150, and the secondconnecting conductor 115 b is electrically connected to the secondelectrode 125 through the substrate 110, the membrane layer 150, and thepiezoelectric layer 123.

Furthermore, in an example, only two via holes 112 and two connectingconductors 115 a and 115 b are illustrated. However, the presentdisclosure is not limited thereto. Based on an embodiment, a greaternumbers of via holes 112 and connecting conductors 115 a and 115 b maybe provided.

The cap 140 protects the element 120 from an exterior of the elementpackage 100 or from an external environment. The cap 140 includes twoside walls 141, each side wall 141 extending from opposite width ends ofthe substrate 110, toward a flat surface covering the element 120. Thecap 140 has a cover shape, with a flat or a curved top surface,including an internal space in which the element 120 is accommodated.Thus, the cap 140 is bonded, soldered, welded, or attached to thesubstrate 110 to allow a side wall 141 of the cap 140 to surround theperiphery of the element 120. Further, a lower surface 141 a of the sidewall 141 is used as a bonding surface that is bonded, soldered, welded,or attached to the substrate 110. In one embodiment, a different,separate structure may be formed in a space between the cap 140 and thesubstrate 110. A material of the cap 140 is not particularly limited.The cap 140 may be made, for example, of a polymer material, such as athermosetting resin or a thermoplastic resin, or may be made of a knownmetal or semiconductor material. However, the present disclosure is notlimited thereto.

FIG. 3 is a schematic enlarged cross-sectional view of region A of FIG.2, in accordance with an embodiment.

Referring to FIG. 3, a bonding portion A, according to an embodiment,includes a protrusion 141P formed on a lower surface 141 a of the sidewall 141 of the cap 140, a first metal layer 171 covering the protrusion141P, a groove 110G formed on the substrate 110, and a second metallayer 172 covering the groove 110G. A metallic bond (MB) is configuredbetween at least a portion of the first metal layer 171 covering theprotrusion 141P formed on the cap 140 and the second metal layer 172covering the groove 110G formed on the substrate 110.

The groove 110G is a recess having an inclined wall surface, as a sidesurface, for line bonding and a flat surface as a bottom surface and isformed on an upper surface 110 c of the substrate 110. The portionhighlighted in a dashed circle in FIG. 3 is the portion of the groove110G in which the first metal layer 171 and the second metal layer 172are in closest proximity to each other or in contact with each other. Inaccordance with an embodiment, the first metal layer 171 covers at leastone surface of the protrusion 141P. For instance, as shown in FIG. 3,the first metal layer 171 extends from a predetermined point on thelower surface 141 a of the side wall 141, covering side surfaces and alower surface of the protrusion 141P, and extending to anotherpredetermined point of the lower surface 141 a of the side wall 141.Furthermore, the second metal layer 172 extends from a predeterminedpoint on the upper surface 110 c of the substrate 110, covering theinclined wall surfaces and the flat surface of the groove 110G, andextending to another predetermined point of the upper surface 110 c ofthe substrate 110.

The MB bonds a portion of the first metal layer 171 covering a corner ora portion of an edge of the protrusion 141P of the first metal layer 171that overlaps with or that faces a portion of the second metal layer 172that covers the inclined wall surface of the groove 110G of the secondmetal layer 172. Thus, an intermetallic bonding surface is not formed ina space between portions of the groove 110G rather than on a planarsurface. Even in the case that a desired total thickness value (TTV) isnot obtained, an insertion depth of the protrusion 141P automaticallyvaries to form a regular bonding line. In other words, self-alignment ispossible, at least, in accordance with an embodiment as illustrated inFIG. 3. Further, even in the case that a bonding line is not formed tohave a very fine pattern of about 1 μm to 2 μm, a line bond is achievedin terms of shape, and the area of an intermetallic bonding surface issignificantly reduced. Further, as the area or the like is increased,when the pressure limit of bonding equipment is exceeded, anintermetallic bonding surface having a fine line width is formed using aplating process, for example, without applying a high level process.

The first and second metal layers 171 and 172 also include metals, suchas copper (Cu) that easily oxidizes, as well as gold (Au) used in acommon metal thermal diffusion process. Further, the first and secondmetal layers 171 and 172 are necessarily made of different types ofmaterials, and may be made of the same type of material because linesformed between side surfaces of metal layers are bonded whilepressurizing surfaces of the metal layers from below, without forming ametallic bond by pressurizing the surfaces. Thus, an internal pure metalis exposed instead of an oxidized surface, so that an easily oxidizedbonding metal, such as copper (Cu), can also be used as a material for athermal diffusion bonding process. Thus, in accordance with one of themany advantages of the present disclosure, manufacturing costs arereduced.

The first and second metal layers 171 and 172 are bonded by a metalthermal diffusion process and stop conduction of heat. Thus, the firstand second metal layers 171 and 172 have a metal thermal diffusion layerformed thereon due to counter diffusion between the first and secondmetal layers 171 and 172.

Furthermore, the groove 110G formed on the substrate 110, and theprotrusion 141P formed on the cap 140 to engage with the groove 110G.This is illustrated in the drawings. However, the present disclosure isnot limited thereto. For example, as long as the cap 140 and thesubstrate 110 form such an MB, the groove 110G may be formed on the cap140, such as the lower surface 141 a of the side wall 141 of the cap140, and the protrusion 141P engaging with the groove 110G may be formedon the substrate 110, such as the upper surface 110 c of the substrate110. In the following description, this will be apparent after anunderstanding of the disclosure of this application through reference tothe appended drawings in their entirety.

FIG. 4 is another example of a schematic enlarged cross-sectional viewof region A of FIG. 2, in accordance with an embodiment.

Referring to FIG. 4, a bonding portion A, according to an embodiment,includes a protrusion 141P formed on a cap 140, a first metal layer 171covering the protrusion 141P, a groove 110G formed on a substrate 110,and a second metal layer 172 covering the groove 110G. The bondingportion A further includes a resin bond formed by a resin layer 177.

The resin layer 177 is disposed or positioned in a space between thesubstrate 110 and the cap 140, for example, in a space between an uppersurface 110 c or a bonding surface 110 c of the substrate 110 and alower surface 141 a or a bonding surface 141 a of the cap 140. The resinlayer 177 bonds the substrate 110 and the cap 140. When the MB and resinbond by the resin layer 177 are simultaneously applied, the MB and theresin bond are combined in a manner of assisting a hermetic seal in anMB region and bonding strength in a resin bonding region, through theresin layer 177.

The resin layer 177 includes known resins, and may include an epoxyresin among the known resins in order to increase bonding strengthobtained by an epoxy bonding process. However, the present disclosure isnot limited thereto.

Method of Manufacturing Electronic Element Package

An example of manufacturing an electronic element package willhereinafter be described. An overlap with the abovementioned descriptionis omitted, and a difference therefrom is primarily described.

FIG. 5 is a schematic cross-sectional view of part of manufacturing anelectronic element package, in accordance with an embodiment.

Referring to FIG. 5, an element 120 is formed on a substrate 110. Theelement 120 is formed by sequentially stacking a membrane layer 150, afirst electrode 121, a piezoelectric layer 123, a second electrode 127,and a protective layer 127 on the substrate 110. A sacrificial layer(not illustrated) is formed prior to the formation of the membrane layer150, and is removed later to form an air gap 130. The first electrode121 and the second electrode 125 are formed as a predetermined patternby forming a conductive layer, depositing a photoresist on an upperportion of the conductive layer, patterning the photoresist using aphotolithography process, and using the patterned photoresist as a mask.

In an embodiment, the first electrode 121 is formed of a molybdenum (Mo)material, and the second electrode 125 is formed of a ruthenium (Ru)material. However, the present disclosure is not limited thereto, and avariety of metals, such as a gold (Au), ruthenium (Ru), aluminum (Al),platinum (Pt), titanium (Ti), tungsten (W), palladium (Pd), chromium(Cr), and nickel (Ni), are used as the first and second electrodes 121and 125, depending on an embodiment. The piezoelectric layer 123 isformed of an aluminum nitride (AlN). However, the present disclosure isnot limited thereto, and various piezoelectric materials, such a zincoxide (ZnO) or quartz, are used. The protective layer 127 is formed ofan insulating material. In an example, an insulating material includes asilicon oxide-based, silicon nitride-based, or aluminum nitride-basedmaterial.

Subsequently, a first connecting electrode 180 and a second connectingelectrode 190 for frequency trimming are formed on upper portions of thefirst electrode 121 and the second electrode 125, respectively. Thefirst and second connecting electrodes 180 and 190 are formed on theupper portions of the first and second electrodes 121 and 125, and arebonded to the first and second electrodes 121 and 125 through theprotective layer 127 or the piezoelectric layer 123. The firstconnecting electrode 180 is formed by removing portions of theprotective layer 127 and the piezoelectric layer 123 by an etchingprocess to externally expose a portion of the first electrode 121, andby depositing gold (Au), or copper (Cu), on the first electrode 121.Similarly, the second connecting electrode 190 is formed by partiallyremoving a portion of the protective layer 127 by an etching process toexternally expose a portion of the second electrode 125, and bydepositing gold (Au), copper (Cu), or the like, on the second electrode125.

Subsequently, use of the first and second connecting electrodes 180 and190 allows filter characteristics of the element 120 to be confirmed anda required frequency to be trimmed, and an air gap 130 is then formed.The air gap 130 is formed by removing the sacrificial layer. As result,the element 120, a resonant portion, is completed.

Furthermore, a cap 140 is formed to protect the element 120 from anexternal environment. The cap 140 is formed by a wafer bonding processat a wafer level. For example, a substrate wafer on which a plurality ofunit substrates 110 are disposed and a cap wafer on which a plurality ofcaps 140 are disposed are bonded to each other to be an integral wafer.In this example, the substrate wafer and the cap wafer bonded to eachother are cut into a plurality of separate element packages in asubsequent cutting process. Further, the cap 140 is seated on thesubstrate 110. The cap 140 and the substrate 110 are heated and pressedto be bonded to each other. A bonding process will be described below inmore detail.

FIG. 6 is a schematic cross-sectional view of part of manufacturing anelectronic element package, in accordance with an embodiment.

Referring to FIG. 6, via holes 112 are formed through the substrate 110,and first and second connecting conductors 115 a and 115 b are formedinside of the via holes 112. The first and second connecting conductors115 a and 115 b are manufactured by forming conductive layers oninternal surfaces 110 a and 110 b of the substrate 110 forming the viaholes 112. For example, the first and second connecting conductors 115 aand 115 b are formed by depositing, coating, or providing conductivemetals (for example, gold (Au) or copper (Cu)) along a first inner wall110 a and a second inner wall 110 b of the substrate 110 forming the viaholes 112.

Also, external electrodes 117 are formed on a lower surface of thesubstrate 110 to complete the electronic element package 100. Theexternal electrodes 117 are formed on the first and second connectingconductors 115 a and 115 b extending to the lower surface of thesubstrate 110. A solder ball formed of Tin (Sn) is used as the externalelectrodes 117, but the present disclosure is not limited thereto.

FIG. 7 is a schematic cross-sectional view of manufacturing region A ofFIGS. 5 and 6, in accordance with an embodiment.

Referring to FIG. 7, a process of bonding the cap 140 to the substrate110 includes forming a first metal layer 171 covering a protrusion 141Pformed on a bonding surface 141 a of the side wall 141 of the cap 140and a second metal layer 172 covering a groove 110G formed in a bondingsurface 110 c of the substrate 110, and bonding the first and secondmetal layers 171 and 172 by a metal thermal diffusion bonding process.

The metal thermal diffusion bonding process is defined as a method thatspreads materials to be bonded, for example, bonding metals, on bothsurfaces of each of wafers to be bonded and pressing the wafers withheat and a strong force to bond the wafers. In one example, the strongforce first functions to press the wafers to have a gap being of a nanosize or less, with which the spread bonding metals may be in closeproximity to each other and diffuse toward each other. The waferspressed in such a manner are heated so that the bonding metals of eachof the wafers diffuse toward each other, thus, bonding the bondingmetals.

As described above, such an MB is formed by bonding a portion of thefirst metal layer 171 covering the edge of the protrusion 141P of thefirst metal layer 171 to a portion of the second metal layer 172covering the inclined wall surface of the groove 100G of the secondmetal layer 172. Thus, an insertion depth of the protrusion 141Pautomatically varies to form a regular bonding line. Further, the areaof an intermetallic bonding surface may be significantly reduced. Also,as the area of the intermetallic bonding surface increases, when thepressure limit of bonding equipment is exceeded, an intermetallicbonding surface having a fine line width is formed using a process, suchas plating or the like, without applying a high level process.

FIG. 8 is a schematic cross-sectional view of another example ofmanufacturing region A of FIGS. 5 and 6, in accordance with anembodiment.

Referring to FIG. 8, a process of bonding the cap 140 to the substrate110 further includes forming a resin layer 177 on the bonding surface141 a of the side wall 141 of the cap 140 or the bonding surface 110 cof the substrate 110, and resin-bonding the bonding surface 141 a of theside wall 141 of the cap 140 to the bonding surface 110 c of thesubstrate 110 using the resin layer 177. As described above, when the MBand the resin bond are simultaneously applied, the MB and the resin bondare combined in a manner to assist a hermetic seal in an MB region andbonding strength in a resin bonding region.

FIG. 9 is a schematic cross-sectional view of a case in which a bondingstructure is applied to an uneven bonding surface, in accordance with anembodiment.

Referring to FIG. 9, an element package to which a bonding structure,according to an embodiment, is applied allows insertion depths ofprotrusions 141P to automatically vary to thus form regular bondinglines, even when bonding heights H1 and H2 are irregular due to a stepST formed on a bonding surface. That is, self alignment is possible.

FIG. 10 is a schematic cross-sectional view of a metallic bondingstructure.

Referring to FIG. 10, in one example, when a first metal layer 171′ anda second metal layer 172′ are formed on a bonding surface of a substrate110′ and a bonding surface of a cap 141′, the bonding surface of thesubstrate 110′ or the cap 141′ is irregular, or the first and secondmetal layers 171′ and 172′ have irregular heights. In this example, whenthe first and second metal layers 171′ and 172′ are metallically bonded,a bonding defect in which portions thereof are not bonded may occur.Thus, such example would create an undesirable outcome.

As set forth above, according to various embodiments, an electronicelement package having a novel bonding structure in which a cap and asubstrate may be firmly bonded regardless of a thickness distributionthereof and a fine bonding line may be formed, and which maysignificantly reduce the bonding area and may lower manufacturing costs,and a method of manufacturing the same may be provided.

While embodiments have been shown and described above, it will beapparent to those skilled in the art that modifications and variationscould be made without departing from the scope of the present disclosureas defined by the appended claims.

For example, the abovementioned embodiments illustrate, as an example,bonding a cap to a substrate and then forming a connecting conductor.However, the present disclosure is not limited thereto, and variousmodifications, such as first forming a connecting conductor and bondinga cap to a substrate are possible.

While this disclosure includes specific examples, it will be apparentafter an understanding of the disclosure of this application thatvarious changes in form and details may be made in these exampleswithout departing from the spirit and scope of the claims and theirequivalents. The examples described herein are to be considered in adescriptive sense only, and not for purposes of limitation. Descriptionsof features or aspects in each example are to be considered as beingapplicable to similar features or aspects in other examples. Suitableresults may be achieved if the described techniques are performed in adifferent order, and/or if components in a described system,architecture, device, or circuit are combined in a different manner,and/or replaced or supplemented by other components or theirequivalents. Therefore, the scope of the disclosure is defined not bythe detailed description, but by the claims and their equivalents, andall variations within the scope of the claims and their equivalents areto be construed as being included in the disclosure.

What is claimed is:
 1. A method of manufacturing an electronic elementpackage comprising: forming an element on a surface of a substrate; andbonding a cap enclosing the element to the substrate, wherein one of thesubstrate and the cap comprises a groove, the other of the substrate andthe cap comprises a protrusion engaging with the groove, and the bondingthe cap to the substrate comprises metallically bonding a first metallayer to a second metal layer, formed in a space between the groove andthe protrusion.
 2. The method of claim 1, wherein the groove comprisesan inclined wall surface, and the metallically bonding of the firstmetal layer to the second metal layer comprises bonding a portion of thefirst metal layer covering an edge of the protrusion of the first metallayer to a portion of the second metal layer covering the inclined wallsurface of the groove.
 3. The method of claim 1, wherein themetallically bonding the first metal layer to the second metal layer isperformed using a metal thermal diffusion bonding process.
 4. The methodof claim 1, wherein the bonding the cap to the substrate furthercomprises resin-bonding the cap to the substrate using a resin layer. 5.The method of claim 4, wherein the resin layer is disposed on either oneor both of the substrate and the cap before the resin-bonding, and isdisposed in a space between the substrate and the cap after theresin-bonding the substrate to the cap.